Conventionally, there are known an oxide semiconductor type, a fuel cell type, an infrared absorption type, a contact combustion type, and the like as detecting methods of ethanol contained in breath, and there are also proposed a technique for stopping start of an engine by detecting an ethanol concentration of a driver, and the like (Japanese Patent Application Laid-Open (JP-A) No. 2004-212217, JP-A No. 2004-279228, JP-A No. 2005-296252, JP-A No. H06-197897, JP-A No. 2007-147592).
Although a skin structure infrared light absorption method and the like are also proposed as a noninvasive measuring method of ethanol in blood, a time lag occurs until ethanol taken into a body reaches blood, from which a problem of a detection time lag arises.
Further, there is proposed a pneumatic infrared detecting apparatus as an accurate non-dispersive infrared analyzer making use of infrared absorption (Readout HORIBA Technical Reports No. 7 July 1993).